Wind Turbine Vane Pitch Control via Balancing and Alignment Weights
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Solution Overview
Problem
Wind turbines with fixed pitch vanes produce negligible torque and power at low rotational speeds, making them inefficient and unstable due to system imbalances and centrifugal forces.
Innovation Solution
A wind turbine pitch control apparatus using balancing and alignment weights attached to the vanes, allowing them to rotate freely and maintain an optimal angle of attack, reducing pitch variations and enhancing torque production at low wind speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fixed pitch vanes are used in a wind turbine, then the structure is simple and stable, but the turbine produces negligible torque and power at low rotational speeds
Solution Approach 1:
A balancing weight is attached to the vane at a first location to counteract the aerodynamic forces and centrifugal effects that cause pitch variation. This counterweight creates a moment that opposes the pitch-changing forces, allowing the vane to maintain a more stable angle of attack while producing torque at low rotational speeds without requiring complex active pitch control mechanisms.
Solution Approach 2:
An alignment weight is attached to the vane at a second location to create an asymmetric weight distribution that generates a moment to align the vane's leading edge perpendicular to the turbine shaft centerline. This asymmetric configuration allows the vane to self-align to an optimal angle of attack position, improving torque production at low speeds without complex control systems.
2Power
If the vane is allowed to rotate freely about the vane shaft to control pitch, then power production at low speeds improves, but pitch variations occur due to centrifugal forces
Solution Approach 1:
The balancing weight is strategically positioned on the vane to counteract the centrifugal forces and aerodynamic moments that cause unwanted pitch variations during rotation. By creating an opposing moment, the balancing weight stabilizes the vane pitch while still allowing the vane to rotate freely to some extent, enabling power production at low speeds without excessive pitch instability.
3Power
If the vane angle of attack is increased to produce more torque at low speeds, then power production improves, but the vane may exceed the stall angle and lose efficiency
Solution Approach 1:
The alignment weight creates a moment that tends to align the vane's leading edge perpendicular to the turbine shaft centerline, which corresponds to a specific angle of attack. This asymmetric weight distribution provides a restoring moment that prevents the angle of attack from exceeding the stall angle, while still allowing sufficiently high angles of attack to produce torque at low speeds. The alignment weight effectively limits the maximum angle of attack to below the stall angle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables wind turbines to self-start and produce power at low wind speeds, reducing the need for external power to reach operating rotational velocity and improving stability by controlling vane pitch and angle of attack.
Implementation Method 1
the balancing weight at the first location eliminates a pitch variation caused by a centrifugal force acting on the vane
Implementation Method 2
the alignment weight at the second location maintains the vane's angle of attack below a stall angle for at least a portion of the rotation of the wind turbine
Data Source
AI summary
Methods and apparatuses for wind turbine vane pitch control including a turbine shaft that transmits mechanical power, a vane support structure that is coupled to the turbine shaft, a vane that is coupled to the vane support structure through a vane shaft, a balancing weight that is coupled to a first location of the vane, and an alignment weight that is coupled to a second location of the vane.